Chains are a nearly ubiquitous component of the mechanical realm, and have been around for ages. Chains are most often comprised of a series of interlocking links or chain links. And in many cases, adjacent links are coupled together by a pin that slides through corresponding apertures of the adjacent links. This type of interlocking chain system is used in a variety of applications, including track chains for heavy equipment. As an example, heavy equipment, such as an excavator or a bulldozer, may include a set of track chains or track groups that include a plurality of links and associated track shoes driven about one or more hubs. The track chains can facilitate forward motion, reverse motion, and turning of the heavy equipment. Segments, sections, or links of this type of track chain are interlocked together via a type of pin often described as a track pin.
During periods of use, the components of the track chain often wear and sometimes fail. Due in part to the forces involved in heavy equipment and the rotational friction between the surface of the track pin and surrounding surfaces, the connection between adjacent links is a possible failure point. Efforts have been made toward enhancing the robustness of the connection between adjacent links, including utilizing sealed and lubricated type connections to yield a track chain that is often described as a Sealed and Lubricated Track (SALT). An example of a conventional track pin-based connection for the SALT configuration is shown in a sectional view in the illustrated embodiment of FIG. 16. Each of the links are coupled together primarily by a track pin and a stepping bushing. In many configurations, the track pin is press fitted through an aperture of the stepping bushing and outer apertures of one of the links. To reduce internal friction between the bushing and the track pin, the track pin in the example embodiment of FIG. 16 is provided with an oil reservoir and an oil passage in fluid communication with the mechanical interface between the track pin and the bushing. This configuration may lengthen the usable life of the connection—but, for a variety of reasons, such as normal wear and tear, the connection can fail or degrade to the point of imminent failure.
It should be understood that not all track chain configurations use a SALT type system. Rather, the SALT type system is described herein to facilitate understanding of a track pin-based track chain for a heavy vehicle or heavy equipment.